A general image forming apparatus of an electrophotographic type has a configuration where toner as developer is supplied to a photosensitive member having an electrostatic latent image formed thereon and a toner image is thus formed and is transferred and fixed on a sheet such as printing sheet. The developing device has a toner accommodation part that accommodates therein toner, an agitator that stirs the toner in the toner accommodation part, a developing roller that supplies the toner to a photosensitive drum, a supply roller that supplies the toner to the developing roller, and the like. The agitator, the developing roller and the supply roller are rotated as the sheet is conveyed (see, for example, JP-A-2006-209010).